[Blackcat]

In addition to a choked fuel filter, check the fuel pickup at the fuel tank, sometimes those can be clogged with algae growth or scum.

 

[Blackcat]

Maybe, you could try diesel purge and see what happens. It won't hurt anything. But the idea of using the vag com to check idle balance is that some cylinders need more fuel than others, it could be because the engine is worn on some cylinders or that there's a fueling issue. Try looking with a vag com tool.